Congenital Hydronephrosis


Hydronephrosis means an increased capacity of the kidney collecting system and signifies dilatation of the kidney pelvis (the connection of the ureter to the kidney) and/or calices of one or both kidneys. The dilation of the upper urinary tract can result from: obstruction, vesicoureteral reflux and a diuretic phenomenon.

  • Congenital hydronephrosis, the most commonly diagnosed uropathy in children, is usually a benign and self-resolving condition.
  • Nonobstructive hydronephrosis does not require operative treatment, while timely treatment is imperative for obstructive hydronephrosis before significant renal damage ensues.
  • Congenital hydronephrosis can be easily diagnosed and monitored using modern ultrasound technology. The diagnosis of such prenatal hydronephrosis is very complex, since a variety of causes can lead to this problem.
  • There is not only one reasonable therapeutic strategy. A conservative approach is always appropriate when there is no risk of permanent kidney damage or complete kidney failure. However, if the children's kidney function is not sufficient, then prompt intervention is required, which may also mean surgery.

Children with congenital hydronephrosis can be divided into three groups based on the causes

Group 1

Blockage in the urinary tract. The urinary tract is made up of the kidneys, ureters, bladder and urethra. The blockage could happen at any point along the urinary tract. Depending on the location of blockage, common conditions we see here are ureteropelvic junction obstruction, ureterovesical junction obstruction with or without ureterocele, posterior ureteral valve. Sometimes there is no structural blockage but the bladder has functional problem in emptying due to underlying disease affecting the nervous system, a condition called neurogenic bladder.

Group 2

Urine flows upward from the bladder back to the ureters and kidneys, a condition called vesicoureteral reflux (VUR). Normally urine only flows in a one-way direction, from the kidney to bladder.

Group 3

Sometimes hydronephrosis is not associated with reflux or blockage. This occurs when there is some delay in the development of the ureters.


  • Prenatally, it may be detected during routine ultrasound examinations.
  • In infants and young children, symptoms may include:
  • Urinary tract infections
  • Poor feeding and failure to thrive
  • Palpable abdominal mass
  • Foul-smelling urine
  • restriction of the kidney function


Fetal ultrasound is a routine test for prenatal care. This is how most of the children with congenital hydronephrosis are diagnosed. Others are found in different settings, for example, following a urinary tract infection, or as an incidental finding when doctors order imaging tests for other problems like abdominal pain.

► Depending on the appearance and severity of hydronephrosis, nephrologists might consider additional imaging studies to determine whether there is obstruction or reflux that has caused hydronephrosis.

Voiding cystourethrogram

Voiding cystourethrogram (VCUG) VCUG is an imaging study of a series of X-rays. It needs a contrast agent that is administered through a catheter into the bladder via the very end point of the urinary tract where urine exits the body. This allows to at the appearance of the bladder, and whether the urine goes upward, as well as the shape of the urethra. VCUG is considered the gold standard in diagnosis of reflux and posterior urethra valve (PUV).

Contrast-enhanced voiding urosonography

Contrast-enhanced voiding urosonography (ceVUS) is a developed later as VCUG dynamic imaging technique that makes also possible to study the structure of the urinary tract after the administration of intravesical contrast material. The main benefit of ceVUS is that it does not use ionizing radiation.

Cintigraphic examinations

Cintigraphic examinations of the kidneys using radiotracers are performed to assess the function of the kidneys and the urodynamic relevance of hydronephrosis and the severity of the obstruction if there is any. The examination is possible after the child is 6-8 weeks old at the earliest, due to the immaturity of the renal tubules. After intravenous administration of a radiotracer (radioactive substance that emits little radiation), a special camera takes a series of images of the child's urinary system.This substance is administered to the child intravenously.To reduce the pain associated with the insertion of an intravenous puncture, a gel or aesthetic cream can be use at the puncture site.The study takes about 1-2 hours to complete.


(Congenital) Hydronephrosis

A hydronephrosis usually will go away as the child grows up, if there is no underlying obstruction or reflux. Congenital hydronephrosis caused by mild obstruction could resolve on its own as well. Children may need repeat ultrasounds and follow up with us for a period of time varying from months to years, before we feel it is safe for discharge. Normally they do not develop advanced renal kidney disease or need specific treatment.


One sided Hydroephrosis

One sided hydronephrosis with an otherwise healthy bladder, even when it is severe, usually has a very good outcome once the obstruction is removed or the reflux gets repaired by a urologist (surgeon who specializes in the urinary tract).


Severe Congenital Hydronephrosis

Severe congenital hydronephrosis can progress to more advanced chronic kidney disease (CKD), including end stage kidney disease (ESKD), especially when both kidneys get involved and the bladder has issues of emptying. As a matter of fact, this is the most common cause of ESKD in children. These children often need multiple surgeries. They require long term follow up with both nephrologists and urologists.

Congenital Hydronephrosis | Upstate Golisano Children's Hospital | SUNY Upstate